The main objective of this research is to further the analysis of functional organization within the cortical structures of the olfactory system. The emphasis is on two structures, the olfactory bulb and the olfactory tubercle. An in vitro preparation of the turtle brain is being developed for the advantages it offers in the analysis of synaptic transmission and local circuits in these structures. The methods will include extracellular and intracellular recordings and analysis of membrane properties, and neuropharmacological studies of putative transmitters, primarily related to dendrodendritic synaptic interactions. Complementing these investigations is the development of computational models to provide specific tests of structure-function relations inferred from the physiological results. These combined studies will provide a systematic approach to local circuit organization, comparable to that being carried out in several other parts of the nervous system. The results should further our knowledge of sensory mechanisms in the olfactory pathway, and give insight into the functions of the olfactory tubercle and its possible implication in dopaminergic forebrain mechanisms and associated behavioral disorders.